It actually is beneficial, and is instinctive. There's a difference between bites (which introduce bacteria deep into punctures where they don't belong) and licking which places nitrites, lysozyme, and other antimicrobials onto the skin. see here: https://www.thelancet.com/journals/lancet/article/PIIS0140-6...
Nevertheless, washing in tap water with soap is probably better nowadays.
Which seems to me like a way to introduce mouth bacteria and cause an infection, but maybe it’s counter-intuitively beneficial?